Motor control system for fuel pumps



March 11, 1952 R. w. JOHNSON 2,589,

MOTOR CONTROL SYSTEM FOR FUEL PUMPS Filed May 5, 1949 5 Sheets-Sheet l MERCURY Mo-roa SAFETY CUT-OUT Lava.

52 Z6 SAFETY FLOAT INVENTOR.

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March 11, 1952 R w JOHNSON 2,589,089 MOTOR CONTROL SYSTEM FOR FUEL PUMPS Filed May 5, 1949 3 Sheets-Sneet 2 Meacuav SwrrcH NORMAL OPE-RATING:

'FLoAT INVENTOR. 1 Rev W. JOHNSON A TTORNE Y.

March 11, 1952 R. w. JOHNSON 2,589,089

MOTOR CONTROL SYSTEM FOR FUEL PUMPS Filed May 5 194 5 Sheets-Sheet 3 SAFETY SWITCH BITMETAI. 9

RIP SWITCH RESET To MER UR Swrr SAFETY FLOAT TRIP SwI-I'cH I I I I I I l I I I INVENTOR. RQY- W. JOHNSON A TTORNE Y.

Patented Mar. 11, 1952 MOTOR CONTROL SYSTEM FOR FUEL PUMPS Roy W. Johnson, Milwaukee, Wis. Application May 5, 1949, Serial No. 91,539

This invention relates to liquid fuel pumping devices of the oil lifter type which are used to pump oil vertically or horizontally from a supply to a burner, heater, furnace, or other similar devices. The usual installation provides for metering the flow from the oil lifter to the burner in accordance with the manual or automatic setting of flow control device.

In the past, oil lifters have usually required a supply pipe and a return pipe connecting the pump to the supply tank. Since the pipe or tube is generally copper, the cost of such an installation is high as well as being more troublesome tha a single pipe system. The Johnson et a1. Patent No. 2,381,756 illustrates a one-pipe oil lifter which utilizes an intermittently operated pump controlled by a float to maintain a constant level in the casing housing the pump. In the event of float failure, a safety float operates to open a valve to recirculate the oil in the casing to prevent flooding or overflow. A bimetal responsive to the heat of the pump motor opened the motor circuit to prevent damage to the motor. While this represented a great advance over the prior art, it was expensive to manufacture. Furthermore, the float operated recirculating valve required a good seal which was diflicult to maintain in some instances. Lastly, when the safety float did operate to recirculate the oil, the prime was frequently lost, resulting in inconvenience.

An object of this invention is to provide a safe, dependable oil lifter which may be manufactured at less cost than prior devices.

Another object is to provide a simplified oil lifter which will maintain its prime under all operating conditions.

Afurther object is to provide a simplified oil lifter which is simple to service and maintain.

Other objects and advantages will be pointed out in, or be apparent from, the specification and claims, as will obvious modifications of the single embodiment shown in the drawings, in which:

Fig. 1 isa perspective view of this oil lifter and has some parts ghosted in to better illustrate the structure.

Fig. 2 is an elevation of Fig. 1; Fig. 3 is a vertical section through Fig. 1; and Fig. 4 is a diagrammatic sketch showing the general principles and wiring of this device.

The above objects are accomplished by means of the oil lifter illustrated in the drawings where a vane pump driven by motor l2 draws oil into casing I4 through inlet 16 past check valve l8. Float 20 normally controls the motor circuit by operating mercury switch 22 while safety switch 4 Claims. (Cl. 318-482) i absorbing starting and stopping shocks.

24 may be opened by safety float 26 in response to an abnormal level in the casing or by bimetal 28 in response to excessive motor heat. Safety switch 24 can be closed by reset 30 only after the abnormal condition has been eliminated. Thus the oil lifter utilizes an intermittently operated pump to maintain a substantiall constant oil level in the casing while the motor circuit is also controlled by means responsive to motor heat or means responsive to an abnormal oil level. Complete safety is provided through prevention of the resetting operation while the abnormal condition exists. The costly recirculating valve assembly required in the Johnson patent (supra) is eliminated as is the problem of mtaintaining an adequate seal in such an assembly.

Turnin now to a more detailed consideration of this invention, it will be noted that motor I2 is mounted on a plurality of supports 32 secured to plate 34 and vane pump in is co-axially hung on struts 35 depending from plate 34. Motor drive shaft 38 is connected by means of spring 40 to intermediate shaft 42 which turns pump rotor 44 through spring 36 to provide a cushioned drive The pump draws oil through inlet I5 past ball check valve l3 and discharges through an outlet (not shown) into pump well 48 and the interior of casing Hi to a level normally controlled by float 20.

Flow from the casing through an outlet (not shown) is regulated by the control employed between the oil lifter and the burner. When the motor operation is interrupted, the ball check seats to retain the prime.

Variations in the oil level in the casing cause float 2c to rise and fall and move supporting arm 53 about pivot pin 52 supported between depending struts 54, 56. When arm 59 moves, it carries link Edwith it to tilt mercury switch 22 about its pivot 'ell on bracket 52 secured to the back of terminal board 54 and open or close the motor circuit. Thus motor :2 is intermittently operated in accordance with the level of the oil in the casing.

Safety switch 56 forms a part of the motor circuit and comprises spring latch 12 and an arm 58 pivctally mounted on the back of the terminal board on pin 16. The lower end of spring latch i2 is riveted to support 74 mounted on panel 64 and the upper end is adapted to project through keeper hole 76 in arm 68. Thus the arm serves as the keeper for the latch. When the arm is raised about its pivot, the latch is released and its inherent resiliency moves it to the position shown in dotted lines in Fig. 3, breaking the motor circuit. If the arm is now permitted to lower, the latch may be reset in keeper 68 by depressing reset 3!! to move the upper end of latch 12 against the inclined end of the keeper. This raises the keeper until further movement of reset 30 permits the keeper to drop with the latch projecting through hole 16. The reset 30 is returned to its original position by spring 18. The casing is, of course, suitably apertured to permit the reset to be operated from outside the casing. It is to be noted that the safety switch cannot be reset as long as the keeper is retained in its elevated position.

The keeper 6% is raised to break the circuit whenever the motor heat or oil level becomes too high. Should the normal operating float 20 fail to function properly to interrupt the motor circuit, the increasing oil level raises float 26 about its pivot 80 to push link 82 upwardly. An insulating member 84 is riveted to link 82 with its narrow upper end projecting through a slot in keeper 68 and guided by a cooperating slot 85 in terminal board 64. The shoulders on member 84 strike the underside of the keeper to raise the keeper and release latch '12 to break the circuit when the safety float rises. The lower end of insulated member 84 may be provided with shoulders normally resting on plate 34 to limit downward movement of the float 2E and of arm 68. It

will now be apparent that an abnormal oil level in casing 14 will trip the safety switch and that the safety switch cannot be reset until the oil level has decreased to normal.

A copper feeler strip 86 is utilized to conduct motor heat to bimetal 28. Both the feeler strip and the bimetal are mounted on block 88 which is secured to plate 34. An actuating arm 90 is riveted to the free end of bimetal 28 and carries a vertical push pin 92, the upper end of which fits into socket 94 in member 96 carried by keeper arm 68. The outer end of actuator 90 is provided with a depending finger 98 which normally rests on plate 34 to prevent pin 92 from withdrawing from the socket. When the motor heats up excessively, the feeler strip conducts the heat to the bimetal which warps upwardly, elevates actuator 90 and pin 92, and lifts keeper 68 until latch 12 trips to open the motor circuit. It will be apparent that the safety switch may not be reset until the motor has cooled off sufficiently to lower keeper 68.

A brief consideration of the manner in which the operation of the various controls may be adjusted to give uniform, accurate operating characteristics is warranted. The main float 20 is prevented from striking the bottom of the casing or from rising to the point where it would interfere with the safety float by limiting movement of the float supporting arm 50 between the upper and lower edges of notch I cut in depending guide 12. The operating range determining the normal oil level variations is regulated by adlusting the positions of nuts I04, I04 on the threaded upper end of link 53 actuating mercury switch 22. The degree of flexure of bimetal 28 required to trip the safety switch may be regulated to determine the trip-out temperature of the motor by turning screw Hi6 threaded into keeper 68 to move the socket member 95 with respectto push pin 92. It will be noted that hole H18 in the terminal board provides access to screw I08.

Although but one embodiment of the present invention has been illustrated and describedjiit will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

I claim:

1. In a fuel pumping device of the type having an electric motor driven pump for drawing fuel into a casing which contains a safety float and a main float with the main float operating a switch in the motor circuit to maintain a given level in the casing, a safety switch in the motor circuit. means connecting the safety float to the safety switch to open the switch when the level exceeds a predetermined level, means responsive to excessive motor heat to open the safety switch, and means for re-setting said safety switch to restore operation of said motor to control by the main float.

' 2. In a fuel pumping device of the type having an electric motor driven pump for drawing fuel into a casing which contains a safety float and a main float with the main float operating a switch in the motor circuit to maintain a given .level in the casing, a safety switch in the motor circuit and including two switch elements, one of the elements normally engaging the other element, means biasing said one element out of engagement with said other element so that opening the safety switch permits said one element to to move out of contact with said other element and break the circuit, means connecting the safety float to the safety switch to open the safety switch in response to an increase in the liquid level above said given level, means for opening said safety switch in response to a predetermined motor temperature, and means for manually resetting said safety switch when the condition occasioning the opening has been eliminated.

3. In a fuel pumping device of the type having an electric motor driven pump for drawing fuel into a casing which contains a safety float and a main float with the main float operating a switch in the motor circuit to maintain a given level in the casing, a safety switch in the motor circuit and including a keeper and a latch, means biasing said latch out of engagement with said keeper, said latch normally engaging the keeper, means connecting the safety float to the safety switch to move the keeper and permit the biased latch to move out of engagement with the keeper and break the circuit in response to an increase in the liquid level above said given level, means responsive to a predetermined motor temperature for moving the keeper out of engagement with the latch to break the circuit, said latch and said keeper remaining out of engagement until manually re-set, and manual means for re-setting said latch in said keeper, said manual means being operable to re-set the safety switch only after the condition opening the safety switch has been removed.

4. In a fuel pumping device of the type having an electric motor driven pump for drawing fuel into a casing which contains a safety float and a main float with the main float operating a switch in the motor circuit to maintain a given level in the casing, a safety switch in the motor circuit and including an arm provided with a keeper hole and mounted for pivotal movement between lower and raised positions and a latch adapted to project into and engage with said keeper hole when the arm is in said lower position, means biasing said latch out of engagement with said keeper hole to break said circuit when said arm is in said raised position, means connecting said safety float to saidarm to raise the arm and release said latch when the level in 5 6 the casing rises above said given level, a bimetal sensitive to the temperature of said motor and R NCES CITED operatively connectiid m fi arm to raise the The following references are of record in the arm to break the circuit in response to a prefil of this patent; determined motor temperature, said arm remain- 5 ing in said raised position until the condition UNITED STATES PATENTS occasioning its elevation has been eliminated, and Number Name Date means for manually re-setting said latch in en- 453,032 Blades May 26, 1891 g gement with said keeper hole, said re-setting 1,935,455 Leland Nov. 14, 1933 means being operable only when said arm is in 10 2,219,472 Defandorf et a1. Oct. 29, 1940 said lower position. 2,381,756 Johnson et a1. Aug. 7, 1945 2,445,069 Johnson July 13, 1948 ROY W. JOHNSON. 2,462,076 Dryden Feb. 22, 194! 

